I have a question from one of my homework sets:
"Let $f(x)$ = cos(sin($3x$)). Find the smallest positive integer $k$ so that $f(x) = f(x + \pi k).$"
I know it's simple, but I'm somewhat confused. If someone could just point me in the right direction, it would be greatly appreciated.
Please don't give the answer, just a little help on how I could arrive to the answer.